035 FXUS63 KFSD 311106 AFDFSD AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SIOUX FALLS SD 606 AM CDT FRI MAY 31 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 423 AM CDT FRI MAY 31 2013 CURRENT UPPER SYNOPTIC SITUATION SHOWS OUR WELL ESTABLISHED UPPER LOW SPINNING AWAY IN SD AT THIS TIME...AND IS LOOSELY TIED TO ANOTHER CIRCULATION ALONG THE BRITISH COLUMBIA COAST. THE SECOND UPPER LOW WILL AFFECT OUR WEATHER NEXT WEEK WHICH IS HIGHLIGHTED BELOW. AT THE SURFACE...LOW PRESSURE IS BEGINNING TO CONSOLIDATE AND STRENGTHEN OVER NORTH CENTRAL SD. THE VARIOUS MODELS ALL CONTINUE TO GRUDGINGLY MOVE OUR UPPER LOW EASTWARD TODAY AND TONIGHT AT A SNAILS PACE...WITH THE WAVE BECOMING MORE OPEN BY EARLY SATURDAY. THE SURFACE LOW FOLLOWS SUIT IN MOVING VERY SLOWLY EASTWARD...AND IT BECOMES QUITE WINDY ON THE BACK SIDE OF THE LOW ARCHING SOUTHEASTWARD INTO OUR SOUTH CENTRAL SD ZONES AND INTO YANKTON TODAY. MOMENTUM WIND TRANSFER IS...OR BECOMES QUITE STRONG IN THOSE AREAS. EVEN WITH CLOUD COVER WHICH SHOULD INHIBIT MIXING POTENTIAL...WINDS NOT TOO FAR OFF THE SURFACE ARE 25 TO 40 KNOTS...WITH THE BEST GRADIENT RIGHT ALONG THE NEBRASKA BORDER. THEREFORE ISSUED A WIND ADVISORY FOR MANY OF OUR MISSOURI RIVER COUNTIES...AT THIS TIME EXCLUDING SIOUX CITY. DECIDED TO BREAK GREGORY AND CHARLES MIX COUNTIES OFF AND RAN THEIR ADVISORY ALL THE WAY THROUGH 06Z SATURDAY AS AM NOT CONVINCED THE WINDS THERE WILL DROP OFF AT ALL AFTER SUNSET. ALMOST EXTENDED IT IN THOSE TWO COUNTIES ALL NIGHT. BUT THE OTHER ZONES SHOULD SEE SOME DECREASE AS THE EVENING PROGRESSES. OTHERWISE AS MENTIONED YESTERDAY...PV USING THE 1.5 SURFACE COUPLED WITH STRONG TROWALING JUXTAPOSED WITH IT...IS THE STORY AS THE DAY PROGRESSES...LINGERING TONIGHT AND RIGHT INTO SATURDAY. THE DYNAMICS CURLS BEHIND THE LOW AND WRAPS INTO OUR FORECAST AREA IN A WEST/SOUTHWEST TO NORTHEAST FASHION. COUPLED WITH A DEEP MOISTURE PROFILE...HIGH POPS ARE WARRANTED THROUGHOUT OUR NORTHWESTERN ZONES TODAY...TAILING OFF TO SCATTERED CHANCES IN SOUTH CENTRAL SD NORTHEASTWARD TO THE BROOKINGS AREA. SHOWERS ARE ALREADY WRAPPING INTO OUR WEST...AND A BIT EARLIER THERE WAS SOME LIGHTNING ASSOCIATED WITH THEM. SO OPTED TO KEEP ISOLATED THUNDER IN WITH THE SHOWER CHANCES FOR OUR WESTERN ZONES TODAY. IN ADDITION TO ALL OF THIS...THE NAM IS STILL SHOWING WHAT COULD BE A BAND OF ISOLATED TO SCATTERED THUNDERSTORMS DEVELOPING IN OUR SOUTHEAST ZONES THIS AFTERNOON ON THE LEADING EDGE OF THE COLD FRONT. BECAUSE OF THE COLD FRONT AND CLOUD COVER...HIGHS WILL BE CONFINED TO THE 60S IN MAY OF OUR SD ZONES...WITH 70S EXPECTED IN MUCH OF SOUTHWEST MINNESOTA AND NORTHWEST IOWA. NOT MUCH CHANGE NEEDED FOR TONIGHT. AS THE MOISTURE...PV AND THETAE TROWALING NUDGES SOUTHEASTWARD...HIGH POPS WILL FOLLOW. LIKELY TO CATEGORICAL POPS ARE WARRANTED FOR OUR AREA...MINUS OUR FAR EASTERN ZONES AND SIOUX CITY. THOSE LOCATIONS SHOW A SHALLOWER MOISTURE PROFILE AND ARE DISPLACED FROM THE STRONGEST DYNAMICS. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 423 AM CDT FRI MAY 31 2013 JUNE 1 SATURDAY STILL LOOKS MORE LIKE A LATE APRIL DAY. CLOUDS... WIND...AND SHOWERS WILL DOMINATE THE AREA. HIGHS STILL LOOK HARD PRESSED TO GET OUT OF THE 50S EXCEPT FOR POSSIBLY ALONG AND EAST OF A SIOUX CITY TO WINDOM MN LINE. BUT RECORD LOW HIGHS ARE SUBSTANTIALLY COLDER THEN WHAT WE HAVE FORECAST. THE UPPER LOW TRANSITIONS INTO AN OPEN WAVE ON SATURDAY AS IT MOVES EASTWARD TOWARD THE NORTHERN MS VALLEY. THEREFORE THE RAIN CHANCES LOOK TO QUIET DOWN SATURDAY AFTERNOON...AND KEPT NO POPS AROUND FOR SATURDAY NIGHT. SUNDAY WILL STILL BE A CHILLY DAY FOR THIS TIME OF YEAR...BUT MORE PLEASANT DUE TO MUCH LESS WIND. WOULD NOT BE SURPRISED TO SEE THE AREA POP A FAIR AMOUNT OF CUMULUS DUE TO A LOT OF WET GROUND IN SOME AREAS AND COLD TEMPERATURES ALOFT. THE MONDAY THROUGH THURSDAY PERIOD WILL BE DOMINATED BY A NORTHERN ROCKIES TROUGH AS IT APPROACHES FROM SOUTHWEST CANADA...THEN MOVES OVER THE AREA AND SLOWS DOWN. FEEL GUIDANCE HAS A GOOD HANDLE ON BRINGING IN A SLIGHT CHANCE OF STORMS MONDAY...WHICH QUICKLY EVOLVED INTO A LIKELIHOOD OF SHOWERS AND STORMS BY MONDAY NIGHT. AFTER THE THREAT PEAKS MONDAY NIGHT AND TUESDAY...THE CHANCES OF PRECIPITATION SHOULD WANE INTO A CHANCE OF SHOWERS AS BACK SIDE OF UPPER LOW LINGERS. WILL GO WITH GUIDANCE HIGH AND LOW TEMPERATURES FOR NOW. THEY LOOK FINE AT THE START...BUT THINK THEY COULD NOT BE COOL ENOUGH BY WEDNESDAY AND THURSDAY. GFS AND ECMWF OPERATIONAL MODELS DIFFER WITH THE ECMWF DEEPER ON APPROACHING TROUGH...BUT THE GFS DOING MORE DIGGING AFTER THE SYSTEM ARRIVES. NOT SURE THAT FAR AHEAD WHICH IS BETTER SO WILL NOT FOOL WITH THE GUIDANCE...IT IS THE GFS WHICH GIVES THE COOLER LATER PERIOD SOLUTION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 555 AM CDT FRI MAY 31 2013 NORTHWEST HALF OF AREA...NORTHWEST OF MML/FSD/PKS LINE WILL SEE CEILINGS 1-3K FEET THROUGH 01/12Z. NUMEROUS -SHRA WITH AREAS VISIBILITY 3-5SM. FROM MML/FSD/PKS AND SOUTHEAST...VFR CONDITIONS WILL BE SLOWLY REPLACED BY CEILINGS 2-3K FEET 18Z-01/06Z...EXCEPT SOUTHEAST OF SUX/SPW LINE ONLY AREAS OF CEILINGS 2-3K FREET. ISOLATED VISIBILITIES 3-5SM IN SCATTERED SHRA/TSRA THROUGH 01/00Z AND IN -SHRA 01/00Z-12Z. SURFACE GUSTS ABOVE 25 KNOTS WILL DEVELOP FROM THE WEST THROUGH 18Z...AND ABATE AFTER 01/00Z. SOME GUSTS ABOVE 35 KNOTS WESTERN PART OF AREA. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...WIND ADVISORY FROM 1 PM THIS AFTERNOON TO 7 PM CDT THIS EVENING FOR SDZ068-069. WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR SDZ057-058-064. WIND ADVISORY UNTIL 1 AM CDT SATURDAY FOR SDZ050-063. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM...MJF LONG TERM... MJF/WILLIAMS AVIATION...